Filtering devices of this kind of construction are known from German laid-open patent application DE-AS No. 18 01 441 and are used for filtering liquids, preferably oil and the like. They have proved their worth in practice. The known filter apparatuses have, however, relatively large constructional dimensions. They require, therefore, correspondingly large mounting spaces which are, however, not frequently available in practice. On account of the large constructional dimensions and the relatively complicated construction of these filtering devices, large inner flow routes result which are disadvantageous in regard to the internal pressure losses as well as in regard to the susceptibility of fouling of the devices. Furthermore, difficult conditions for the maintenance and the cleaning of these filtering devices result from this kind of construction.
Efforts for a long time in the filter technology have been made to produce filtering devices of the smallest possible constructional dimensions and to design them in such a way that mounting, maintenance and cleaning of these devices is rendered as simple as possible. However, such efforts have not succeeded in producing a flush-back filter of the aforementioned construction which fully meets all these requirements. It is therefore the task of the invention to improve particularly the flush-back filter known from the the DE-AS No. 18 01 441, the disclosure of which is incorporated herein by reference, in such a way that it can be manufactured with considerably smaller overall dimensions. The filter apparatus has to meet at the same time also the other requirements mentioned above, like the simplest possible mounting, maintenance and cleaning.